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AF 447 Thread No. 12

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AF 447 Thread No. 12

Old 8th Jun 2017, 15:11
  #1461 (permalink)  
 
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Originally Posted by john_tullamarine View Post
Neither of the other two could have done any better, using available data from CVR.

.. many of us would have thought that it just needed someone to look at the AH for a moment (obviously, there was no semblance of an instrument scan in the cockpit at the time ..) and wonder why the body angle was up where it was ... not rocket science for those who have a good grounding in stick and rudder I/F, I would think.
It is my surmise that it was the Horizon to which PM was pointing: "Here, and here, you go up....so go DOWN"

Also, Captain DuBois: "Take this.......Watch your lateral!!"

From the CVR... Wondering about what was working and what was erroneous was their plight, they hadn't the benefit of Recorders, and seven years on.....

Just what the situation calls for, Autotrim into a non recoverable Stall. As if....all was normal? Autotrim, in its insidious way, foreclosed recovery; every second of Nose Up bias it supplied cemented their doom. Trim is for cruise, not for maneuvering out of unusual attitudes....
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Old 8th Jun 2017, 18:29
  #1462 (permalink)  
 
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Concours, what you postulating may be true once the stall was completely developed - my point is that it should never have gotten that far.
Ask any first year Aero student this question:
"You're at a stable 35k cruise, then pull full nose up and leave it there, what will happen?"
They'll respond along the line of "you'll climb - trading airspeed for altitude".
And if you keep the stick full back, what then?
"Why would you do that, you'll stall!"
What I can't understand (and can't forgive) is why Bonin didn't know that basic fact...
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Old 8th Jun 2017, 19:02
  #1463 (permalink)  
 
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People seem to seek clean-logical data that logic and engineering can explain. Life isn't like that.

The best explanation for AF447 are the first three sentences of this quote from Frank Herbert's "Dune".
“I must not fear. Fear is the mind-killer. Fear is the little-death that brings total obliteration. I will face my fear. I will permit it to pass over me and through me. And when it has gone past I will turn the inner eye to see its path. Where the fear has gone there will be nothing. Only I will remain.”
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Old 8th Jun 2017, 19:40
  #1464 (permalink)  
 
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Originally Posted by tdracer View Post
What I can't understand (and can't forgive) is why Bonin didn't know that basic fact...
To me, the answer is easy. There are 2 types of knowledge in play.

First, there's academic knowledge, like the facts recited by your hypothetical aero student. For the lazy, it amounts to little more than flashcard-type question and response that's unconnected to anything. Sometimes, for a more diligent pilot, some of these facts can start getting processed into logical relationships and connected into some small webs of theory. And maaaybe, if we're lucky, sometimes even connected to... the physical realm of actual flight!

Second (and, unfortunately, a world apart) is the other type of knowledge, which isn't really a type of knowledge, but I'm talking about the gut-level, split-second urges to make various control inputs in response to aircraft states. For the most part, these urges aren't at all informed by any theory of flight from the first type of knowledge, but rather quick-reacting, unthinking, "twitch" type responses that are either instinctual, or drilled to a level where they might as well be instinctual. Now in some areas of flight, this is fine. If you're flying straight and level, the gut response to a slight bank upset is to roll the wings level. If a gust of turbulence knocks the nose up, you push it back down. If it knocks it down, you pull it back up. If you're rolling down the centerline and the plane starts coming left, you push on the right rudder, etc.

(Note that this drilling for the responses of these simple situations can come not just from the beginning of that person's flight training, but since they are a child. The pertinent example of this is the general principle that you control a vehicle by pointing its front end in the direction you want to go. We know (and have internalized this) since we were children and learned basically how cars work.)

But in other areas, this gut-level instinctual knowledge will lead us astray. If have a large attitdue upset, that leaves you upside down and with the nose below the horizon, the drilled response of the "pull the yoke back" (which is normally the go-up control) will of course only exacerbate the situation. A successful outcome requires an application of the first type of (academic) knowledge, an understanding of the lift vector and its manipulations (I wrote more about this here in the recent thread about upset recovery). Understanding aerodynamics is not just for answering test questions for getting your license, it really really applies! But too many only take it as far as it satisfies the licensure task.

This yoke-pull go-up response is unfortunately drilled into us way too far not only from the common-sense notion that vehicles go where you point their noses (outside aviation) but even inside aviation-

- from the 99% of our flying time which is spent on the front side of the power curve and therefore the airplane indeed does go up when the nose goes up

- from lazy and unknowledgable instructors that don't explain the real-life ramifications of the drag curve and the relationship between excess thrust and flight path angle

- from lazy application of technology, i.e., autothrottles that also hide that same ramification, ...

- from all those things that suffuse a pilot's career and drill the yoke-pull go-up response so deep into a pilot't gut reaction. Considering all these factors, it's absolutely unsurprising that when this pilot was suddenly faced with mismatching info, and every alarm under the sun going off at once, that he was too wide-eyed and unable to use some dim factoid he used to pass a written test decades ago, to override the gut-level reaction to pull the stick back.

You just can't overcome this starting with when the shit hits the fan in flight. It starts with an intellectual drive to deeply understand the mechanics of flight, and to apply that academic knowledge into thinking (on the ground) about what and why the airplane is gonna do when this and that happens, and what and why would then the proper pilot response be. It's a process that starts when you first crack your student pilot manual, repeats itself continuously throughout your career, and doesn't end until your last flight.

One of the chief tasks of a good instructor (for other peoples minds) and a good learner (for one's own mind) is to bridge the gap between these 2 types of knowledge. The first one is useless without application to the secondd, and the second is deadly without application from the first.
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Old 8th Jun 2017, 19:57
  #1465 (permalink)  
 
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Anytime I get on this topic, I think of this very illustrative passage by Richard Feynman about a long visit to Brazil and his experience of their physics education system. Here is the entire chapter from his book, below is a shorter excerpt. (A little malformatted, unfortunately)

In regard to education in Brazil, I had a very interesting experience. I was teaching a group of students who would ultimately become teachers, since at that time there were not many opportunities in Brazil for a highly trained person in science. These students had already had many courses, and this was to be their most advanced course in electricity and magnetism – Maxwell’s equations, and so on.
The university was located in various office buildings throughout the city, and the course I taught met in a building which overlooked the bay.
I discovered a very strange phenomenon: I could ask a question, which the students would answer immediately. But the next time I would ask the question – the same subject, and the same question, as far as I could tell – they couldn’t answer it at all! For instance, one time I was talking about polarized light, and I gave them all some strips of polaroid.
Polaroid passes only light whose electric vector is in a certain direction, so I explained how you could tell which way the light is polarized from whether the polaroid is dark or light.
We first took two strips of polaroid and rotated them until they let the most light through. From doing that we could tell that the two strips were now admitting light polarized in the same direction – what passed through one piece of polaroid could also pass through the other. But then I asked them how one could tell the absolute direction of polarization, for a single piece of polaroid.
They hadn’t any idea.
I knew this took a certain amount of ingenuity, so I gave them a hint: “Look at the light reflected from the bay outside.”
Nobody said anything.
Then I said, “Have you ever heard of Brewster’s Angle?”
“Yes, sir! Brewster’s Angle is the angle at which light reflected from a medium with an index of refraction is completely polarized.”
“And which way is the light polarized when it’s reflected?”
“The light is polarized perpendicular to the plane of reflection, sir.” Even now, I have to think about it; they knew it cold! They even knew the tangent of the angle equals the index!
I said, “Well?”
Still nothing. They had just told me that light reflected from a medium with an index, such as the bay outside, was polarized; they had even told me which way it was polarized.
I said, “Look at the bay outside, through the polaroid. Now turn the polaroid.”
“Ooh, it’s polarized!” they said.
After a lot of investigation, I finally figured out that the students had memorized everything, but they didn’t know what anything meant. When they heard “light that is reflected from a medium with an index,” they didn’t know that it meant a material such as water. They didn’t know that the “direction of the light” is the direction in which you see something when you’re looking at it, and so on. Everything was entirely memorized, yet nothing had been translated into meaningful words. So if I asked, “What is Brewster’s Angle?” I’m going into the computer with the right keywords. But if I say, “Look at the water,” nothing happens – they don’t have anything under “Look at the water”!
Later I attended a lecture at the engineering school. The lecture went like this, translated into English: “Two bodies… are considered equivalent… if equal torques… will produce… equal acceleration. Two bodies, are considered equivalent, if equal torques, will produce equal acceleration.” The students were all sitting there taking dictation, and when the professor repeated the sentence, they checked it to make sure they wrote it down all right. Then they wrote down the next sentence, and on and on. I was the only one who knew the professor was talking about objects with the same moment of inertia, and it was hard to figure out.
I didn’t see how they were going to learn anything from that. Here he was talking about moments of inertia, but there was no discussion about how hard it is to push a door open when you put heavy weights on the outside, compared to when you put them near the hinge – nothing!
After the lecture, I talked to a student: “You take all those notes – what do you do with them?”
“Oh, we study them,” he says. “We’ll have an exam.”
“What will the exam be like?”
“Very easy. I can tell you now one of the questions.” He looks at his notebook and says, ” ‘When are two bodies equivalent?’ And the answer is, ‘Two bodies are considered equivalent if equal torques will produce equal acceleration.’ ” So, you see, they could pass the examinations, and “learn” all this stuff, and not know anything at all, except what they had memorized.
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Old 8th Jun 2017, 21:17
  #1466 (permalink)  
 
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Originally Posted by tdracer View Post
Concours, what you postulating may be true once the stall was completely developed - my point is that it should never have gotten that far.
Ask any first year Aero student this question:
"You're at a stable 35k cruise, then pull full nose up and leave it there, what will happen?"
They'll respond along the line of "you'll climb - trading airspeed for altitude".
And if you keep the stick full back, what then?
"Why would you do that, you'll stall!"
What I can't understand (and can't forgive) is why Bonin didn't know that basic fact...
You make conclusions with insufficient evidence, and do not allow for facts established!

At loss of Autopilot, along with cavalry charge and Master Caution, there was.....STALL STALL....

May I then ask your question of the aircraft: "It should never have gotten 'that far' "

The pilot had nothing to do with the initial warning, save perhaps his initial input of NU.

If you fly this aircraft, and have an explanation for "mayonnaise stirring", enlighten us as to the link between this first Stall warning and the aircraft's attitude?
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Old 8th Jun 2017, 21:45
  #1467 (permalink)  
 
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240 KTS ??? no, 107 KTS

Originally Posted by Concours77 View Post
In descent, 447's airspeed (velocity) was seldom below 300 knots. Indications were what put them in the grinder in the first place. So any discussion of indications or "How bad was the Stall", are meaningless.

She impacted with a velocity around 240 knots.

"sixty knots" is extraneous information. A pilot who confuses a reoccurring Stall Warn and increasing velocity with decreasing Pitch such that he pulls back, is too in the weeds to fly. Neither of the other two could have done any better, using available data from CVR.

jmo
From the BEA final report:

"Les dernières valeurs enregistrées sont une vitesse verticale de - 10 912 ft/min, une vitesse sol de 107 kt, une assiette de 16,2 degrés à cabrer, un roulis de 5,3 degrés à gauche"

So I understand that VS and GS were the same 107 KTS at impact.

I am wondering why would a Ground Speed be only displayed on the ND, and not on PFD? Isn't it a strange design?
A glance at GS and you can guess if a stall condition might exist, at any altitude. To have to look at the ND is not optimum in such a scenario.
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Old 8th Jun 2017, 22:21
  #1468 (permalink)  
 
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Even in the jetstream? No, there are plenty of air-data sources there to diagnose a stall. Groundspeed cluttering the PFD would be absurd.
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Old 8th Jun 2017, 23:11
  #1469 (permalink)  
 
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Nonsense. They never got to 300 kts. They got to 160 KIAS and 130 KIAS. They hit with zero and unknown. The unknown readout had been 0-30 KIAS just prior to impact.

Page 93 of the report -

https://www.bea.aero/docspa/2009/f-c...p090601.en.pdf
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Old 9th Jun 2017, 17:33
  #1470 (permalink)  
 
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Vessbot

I meant that if you see, say 250 GS at FL350, and you have a stall warning, it might help to recognize a stall. If a crew is mislead by multiple failures, Ground Speed is there to give an independant speed data.

When GS is not on PFD, it is not in the primary scan. I am wondering if this could be a contributing factor. Like the side stick thing : proper design ?
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Old 9th Jun 2017, 19:28
  #1471 (permalink)  
 
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Originally Posted by misd-agin View Post
Nonsense. They never got to 300 kts. They got to 160 KIAS and 130 KIAS. They hit with zero and unknown. The unknown readout had been 0-30 KIAS just prior to impact.

Page 93 of the report -

https://www.bea.aero/docspa/2009/f-c...p090601.en.pdf

Hi. With great respect, there is an element of nonsense about the report, in that it purports to display actual in the moment data. Nothing wrong with that, but without a studious representation, inclusive of actual audio, blanket statements are not iron clad.

From data in the report, many explanations can be supported, but remain conjecture.

Was there not a data point that showed 15,000 feet per minute descent? Now that is 150 knots in the vertical, and suggests that with the concurrent horizontal velocity, a value approaching a velocity of 300 knots is supportable.

Without reliable IAS, I put more faith in the report of "crazy speed" than any numerical value of record?

As to loss of Stall warn below "sixty knots"? Would the pilot believe they had regained aero flight with the display con current with the re invigorated Stall Warn? If in fact the aircraft was reporting accurately, wouldn't the pilot misread Stall cues as something other than Stall?

In other words, as the aircraft AoA reduced, and Stall was announced, the associated buffet, roll problem, and increase in noise level was understood as overspeed, rather than Stall? His move to spoilers would suggest that.

So, again, with respect, the dynamic flight cues are missing from the report, and I choose to keep my conclusions open...
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Old 11th Jun 2017, 14:49
  #1472 (permalink)  
 
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Originally Posted by FLEXJET View Post
Vessbot

I meant that if you see, say 250 GS at FL350, and you have a stall warning, it might help to recognize a stall. If a crew is mislead by multiple failures, Ground Speed is there to give an independant speed data.
I understood that from your previous post. I don't know your background, but your premise forces me to spell out what's obvious to trained pilots: groundspeed has no effect on stall. Airspeed (the aircraft's movement through the airmass that it's in) determines that. If you're flying into a 250 knot headwind at a 250 knot airspeed, the groundspeed will be zero and that indicates nothing at all dangerous. I have personally "hovered" a plane like that.

To use that data meaningfully, first the crew would have to convert the winds aloft to a head/tailwind component, next add it to the groundspeed to get a true airspeed, and finally convert that to an indicated airspeed at attitude. This is the kind of stuff there used to be a 4th crewmember for. The notion that someone already as task saturated and confused as the crew in question, be able to quickly do that problem off the cuff successfully and use it to get themselves out of the pickle, is ludicrous.

GS would not have helped, and would only be unnecessary clutter on the PFD.

Last edited by Vessbot; 11th Jun 2017 at 15:11.
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Old 11th Jun 2017, 17:12
  #1473 (permalink)  
 
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thanks for answering

I am a bizjet guy, EASA/FAA. While in cruise, I usually see a GS range of 380/620KT.

In the case of AF447, while stalling for 3 minutes, would you agree that their GS was much below that range?
Would you agree that a quick look at the OFP will give the expected and accurate GS to be compared with?

The crew checked engine parameters but I never read in the report that GS was mentioned or discussed.
I am just wondering if checking / discussing / comparing GS could have reversed this tragic fate, i.e. could have made someone finally push the stick (again, Airbus design, sorry to insist...).
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Old 11th Jun 2017, 17:41
  #1474 (permalink)  
 
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Although it would be a reach, it would not necessarily be wrong to say the crew confused attitude with altitude, and power with airspeed.

Though unlikely, that would explain their obsession with power, and the "need" for Nose Up?
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Old 11th Jun 2017, 20:27
  #1475 (permalink)  
 
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They had reliable airspeed indicators except for a very short time. One was only reliable for 47(?) seconds, both were u reliable for about 29(??) seconds.

"Nose up" was the low altitude training procedure for stalls. Assumes a higher thrust to weight ratio, denser air, and Normal Law. Piloting 101, and physics, especially high altitude physics, disagree.
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Old 11th Jun 2017, 22:09
  #1476 (permalink)  
 
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Actually, it was the procedure for "approach to Stall", no? This aircraft cannot be Stalled in Normal Law?

Halfway through the descent, Captain suggests to Bonin: "...Try Climb..." Bonin replies, "...But I have tried that for some time now...!"

Captain did not respond, as I recall... Whatever the attitude at that specific moment (it could be determined with CVR indexed to NU graph) the Captain thought Nose Up was appropriate!!

That would be instructive, at least as to Captain's efforts to recover?


@Winnerhofer. Was there ever a conformed video representation of attitude, controls, VS, etc.?

Last edited by Concours77; 12th Jun 2017 at 15:26. Reason: Add question for Winnerhofer
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Old 13th Jun 2017, 11:35
  #1477 (permalink)  
 
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This topic, transcending the peculiarities of stall recovery with the airbus family of a/c, notably the use of trim, raises the same issue over and over again relating to Uprt-Loc phenomenon which did not exist in the past.

The whole point, is how the crews can revert to " Back to basics" and with their situational awareness and visual cues they get from proper scanning and understanding from their instruments and basic pitch and power setting comprehension, do the right things, and save the day and instead of digging holes in the ground or splash at sea..

But what does " Back to basics" involve ?

For the previous generation of pilots, moving to the new generation of fully automated aircrafts, it meant applying their skills both mental and motor, to fly the aircraft the way they used to fly a Constellation or a 707 or a DC8 or aDC9

They had an extensive experience with "Classic" jets they had flown for decades and they were able to step back into known territory,

They successfully terminated the flight managing situations that their automated systems were unable to cope with.

In 1995 pilots flying the new generation aircrafts still had extensive experience with the older jets

Ten to fifteen years after this was not the case anymore. We saw the advent of a new generation of pilots trained and rated with the new automated aircrafts lacking the experience of their predecessors.

To them, "Back to Basics" has no meaning at all, they cannot revert to "Basics" they dont have.

The rule "Back to basics" is no longer applicable
In case of need, we find pilots trained on the new generation of aircrafts having to deal with scenarios that were the daily bread of older generation of pilots and here they are clueless.

They find themselves in situations they are unable to either comprehend or analyse, which however "basic" they could have been for the older generation,
have no meaning for them, hence the numerous accidents.

This is the major issue involving crews which have never known neither flown the old generatuon of aircrafts.

How newly introduced Uprt-Loc training, involving limited on air exercises and sim sessions will solve the problem escapes my common sense and understanding.....

Last edited by markkal; 13th Jun 2017 at 18:32.
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Old 13th Jun 2017, 19:23
  #1478 (permalink)  
 
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I can see your point but unless I'm mistaken Bonin was an experienced glider pilot. He must have sensed something was not adding up...
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Old 14th Jun 2017, 05:24
  #1479 (permalink)  
 
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His glider experience didn't helped with the stall of a swept wing, at cruise altitude.
The stall warning was not triggered continuously during the stalled condition, but it was triggered when not suppose to. I believe this aspect was never discussed.
On the A330 as on other aeroplanes of the same generation, the threshold of the stall warning varies with the Mach, in such a way that it is triggered - in alternate or direct law – before the appearance of buffet.
The stall warning was triggered at 2 h 10 min 51, 10 seconds later the variometer indicated a solid climb of 2000 ft/min and the vertical acceleration was around 1g. In less than a minute, the aircraft vertical speed exceeded -15000 ft/min with associated aerodynamic noise of the increased airspeed (in wrong direction).
Now, the conventional stall of a glider: almost zero aerodynamic noise, clear buffet, 0 g, the natural drop of the nose, the aerodynamic noise rapidly increased. An experienced glider pilot estimates the speed by aerodynamic noise.

https://youtu.be/7QpUj7wiPDI
Well Bonin never recovered from his steep dive.
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Old 14th Jun 2017, 07:02
  #1480 (permalink)  
 
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Yes Atakacs and Phoenix, you have a point there, but am still puzzled, pitch & power = performance, and "power" for a glider pilot comes from gravity, so the nose has to go down e.g. the yoke forward....
And what about "Tunnel vision" or the lack of instrument scanning....ASI malfunction alone should not cripple a pilot, worse a crew...

From the transcripts and reactions of the crew, it appears they did not panic so fear was not a crippling factor at least at the beginning..

Last edited by markkal; 14th Jun 2017 at 10:11.
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